8 bit grayscale

Images that contain 256 (2⁸=256) possible shades of gray needed to represent most black and white photos accurately. 256 levels of gray is actually more shades of gray than the human eye can see.

24 bit color

24-bit color images are composed of three 8-bit color channels. When combined, the red, green and blue channels provide up to 16.7 million possible combinations (hence, colors). 24-bit color is also known as True Color and photo-realistic color.

36 bit color

36-bit color images are composed of three 12-bit color channels. When combined, the red, green and blue channels provide up to 68.7 billion possible combinations that translate into that many "colors." (This compares to 16.7 million colors for 24-bit scanners.) The extra amount of information that can be processed by 36-bit scanners translates to more vivid color reproduction, as the scanner is able to accommodate more subtle gradations of color approaching lifelike accuracy.

Aberration

The failure of an optical lens to produce an exact point-to-point correspondence between the object and its resulting image. Various types are chromatic, spherical, coma, astigmatism and distortion.

Absorption

The loss of light of certain wavelengths as it passes through a material and is converted to heat or other forms of energy.

Accuracy

The extent to which a machine vision system can correctly measure or obtain a true value of a feature. The closeness of the average value of the measurements to the actual dimension.

Active Illumination

Lighting a scene with a light source coordinated with the acquisition of an image. Strobed flash tubes, pulsed lasers and scanned LIDAR beams are examples.

AGC

Automatic Gain Control. A circuit for automatically controlling amplifier gain in order to maintain a constant output voltage with a varying input voltage within a predetermined range of input-to-output variation.

Algorithm

A set of well-defined rules or procedures for solving a problem or providing an output from a specific set of inputs.

Alpha Risk (ý-risk)

The risk of rejecting good product.

Ambient light

Light which is present in the environment of the imaging front end of a vision system and generated from outside sources. This light, unless used for actual scene illumination, will be treated as background noise by the vision system.

Analog

A smooth, continuous voltage or current signal or function whose magnitude (value) is the information. From the word "analogous," meaning "similar to."

Analog-to-Digital Converter (A/D)

A device which converts an analog voltage or current signal to a discrete series of digitally encoded numbers (signal) for computer processing. Architecture for a vision system, the hardware organization designed for high speed image analysis.

Aperture

In television optics, it is the effective diameter of the lens that controls the amount of light reaching the photoconductive or photoemitting image pickup sensor.

Aperture Correction

Compensation for the loss in sharpness of detail because of the finite dimensions of the image elements or the dot-pitch of the monitor.

Area

Portion or area of the image to be analyzed. Area analysis measures the number of pixels which fall in a specified range of gray levels for the feature of interest.

Area Array Camera

A solid state imaging device with both rows and columns of pixels, forming an array which produces a 2D image.

Array Processor

A specially designed vision engine peripheral which attaches to the host to speed up arithmetical calculations by using parallel processing techniques. The host manages image data access and analysis results.

Artifact

An artificially created structure (by accident or on purpose), form or shape, usually part of the background, used to assist in measurement or object location.

Artificial Intelligence

The capability of a computer to perform functions normally attributed to human intelligence, such as learning, adapting, recognizing, classifying, reasoning, self-correction and improvement. Rarely found connected to vision systems.

ASIC

An acronym for Application Specific Integrated Circuit. All vision system elements including firmware can be integrated onto one ASIC.

Aspect ratio

The ratio of the width to the height of a frame of a video image. The U.S. television standard is 4:3 or 1.333

ASPI

Stands for Advanced SCSI Programming Interface. ASPI is a protocol or language developed by the Adaptec Corporation to allow communication between SCSI peripherals (like a scanner) and an interface card.

Astigmatism

A defect in a lens which causes blur or imperfect image results, since the rays from a given point fail to meet at the focal point.

Asynchronous

A camera characteristic which allows the return to top-of-frame to occur on demand, rather than synchronously following the 60 hz power line scanning frequency.

Attenuation

In general terms, a reduction in signal strength.

Attribute List

List of distinguishing features which are selected for IP calculation.

Auto Balance

A system for detecting errors in color balance in white and black areas of the picture and automatically adjusting the white and black levels of both the red and blue signals as needed for correction.

Autofocus

The ability of an imaging system to control the focus of the lens to obtain the sharpest image on the detector. Edge crispness is a typical control variable.

Automatic Gain Control

A process by which gain is automatically adjusted as a function of input or other specified parameter.

Automatic Iris Lens

A lens that automatically adjusts the amount of light reaching the imager.

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Back Porch

That portion of the composite picture signal which lies between the trailing edge of the horizontal sync pulse and the trailing edge of the corresponding blanking pulse.

Background

The part of a scene behind the object to be imaged.

Backlighting

Placement of a light source behind an object so that a silhouette of that object is formed. It is used where outline information of the object and its features is important rather than surface features.

Backpropagation

A training technique which adjusts the weights of the hidden and input layers of a neural net to force the correct decision for a given feature vector data input set.

Baffle

A type of shield that prohibits light from entering an optical system.

Bandpass Filter

An absorbing filter which allows a known range of wavelengths to pass, blocking those of lower or higher frequency.

Bandwidth

The number of cycles per second (Hertz) expressing the difference between the lower and upper limiting frequencies of a frequency band; also, the width of a band of frequencies.

Bar Code

An identification system that employs a series of machine-readable lines of varying widths of black and white. Usually read with a laser scanner.

Bar Code (2D)

An arrangement of rectangles and spaces that contains far more information than a traditional bar code.

Barrel Distortion

An optical imperfection which causes an image to bulge convexly on all sides similar to a barrel.

Beamsplitter

An optical device which divides one beam into two or more separate beams. A simple coated piece of glass in the optical path might reflect 60% of the light down onto the object, while allowing the other 40% to pass.

Beta Risk

The risk of accepting bad or defective product.

Binary

An image with pixel values either one or zero.

Binary image

A black and white image represented as a single bit containing either zeros and ones, in which objects appear as silhouettes. The result of backlighting or thresholding.

Bit

An acronym for a Binary digit. It is the smallest unit of information which can be represented. A bit may be in one of two states, on or off, represented by a zero or a one.

Bit Map

A representation of graphics or characters by individual pixels arranged in rows and columns. Black and white require one bit, while fancy high definition color up to 32.

Blanking

The time during a raster scan retrace when the video signal is suppressed.

Blob

A single, connected region in a binary or grayscale image.

Blob Analysis

Identification of segmented objects in an image based on their geometric features (ie area, length, number of holes). (SRI)

Blooming

The defocusing of regions of the picture where the brightness is at an excessive level, due to enlargement of spot size and halation of the fluorescent screen of the cathode-ray picture tube. In a camera, sensor element saturation and excess which causes widening of the spatial representation of a spot light source.

Borescope

A device for internal inspection of difficult access locations such as pipes, engines, rifle barrels and pipes. Its long narrow tube contains a telescope system with a number of relay lenses. Light is provided via the optical path or fiber bundles. A 45 degree mirror at the end allows inspection of tube walls.

Boundary

The line formed by the joining of two image regions, each having a different light intensity. The edge of a region or object.

Bounding Box

The four coordinates which define a box around the object parallel to the major and minor axis. (SRI feature)

Brewster's Angle

The angle at which incident light, by reflecting at a boundary between two mediums of different refractive indices (ie air/glass or air/water), becomes plane polarized. For air/glass it is about 67.4 degrees.

Brightness

The total amount of light or incident illumination on a scene or object per unit area. Also called intensity.

Brightness

The attribute of visual perception in accordance with which an area appear to emit more of less light. (Luminance is the recommended name for the photo-electric quantity which has also been called brightness.)

Bus

A local area network inside a computer which electrically connects all cards. They all hear the same information.

Byte

Eight bits of digital information. A byte has values from 0 to 255, and is the unit most common to represent the gray scale value of one pixel.

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Calibration

The act of relating X and Y pixel spacing to a known or predetermined pixels per unit length (ie inch, mm) factor. Often involves adjusting the imager position in setup.

CCD

Charge Coupled Device. A photo-sensitive image sensor implemented with large scale integration technology.

CCD

Frame Transfer CCD. The entire image is transferred from the sensing area to a storage area on chip. Data (charge) is read out from the storage area in a full frame mode. This workhorse of the industry is also capable of non-RS-170 operation.

CCD

Interline Transfer CCD. Data (charge) is transferred simultaneously out by odd and even lines or fields directly from the image sensors to their corresponding sensor registers. The output from the camera is always one field (frame) behind the image being captured.

Centroid

The center of mass of an object having a constant density, or of an object having varying density, weighted by the gray scale value.

Character

A single letter, digit or punctuation symbol requiring one byte storage.

Character Recognition (OCR)

Imaging and recognizing individual characters in a scene. Also called Optical Character Recognition.

Character Verification (OCV)

Imaging and verifying the correctness, quality and legibility of known characters in an image. Also Optical Character Verification.

Child

An object wholly contained within another object called the parent (SRI). A washer, including the hole, is the parent, and the hole is the child.

Chroma

The quality of a color including both the hue and saturation. Not present in gray.

Chromatic Aberration

An optical defect of a lens which causes different colors or wave lengths of light to be focused at different distances from the lens. It is seen as color fringes or halos along edges and around every point in the image.

Chromaticity

The color quality of light which is defined by the wavelength (hue) and saturation. Chromaticity defines all the qualities of color except its brightness.

Chrominance

A color term defining the hue and saturation of a color. Does not refer to brightness.

Chrominance Signal

That portion of the NTSC color television signal which contains the color information.

CID Charge Injection Device

A photo-sensitive image sensor implemented with large scale integration technology. Based on charge injection technology, a CID can be randomly addressed, non-destructively read, can be subscanned in a small region and is less susceptible to charge overflow from bright pixels to neighbors. The pixel structure is contiguous with maximum surface to capture incident light which is useful for sub-pixel measurement.

CIE

An acronym for a chromaticity coordinate system developed by the Commission Internationale de l'Eclairage, the international commission on illumination. In the CIE system, a plot of ratios (x, y and z) of the three standard primary colors (tristimulus values) to their sum. The most common diagram is the 2 dimensional CIE (x,y).

Classification

Assignment of image objects to one of two or more possible groups. Decisions are made by evaluating features either 1) structurally based on relationships or 2) statistically. For example, 1) a penny is round, a certain diameter (+/- a tolerance) and has a histogram of a mean value; or 2) statistically, the object is measured a number of times, then the average and standard deviation are recorded. After training the features are weighted based on significance in object identification. For multiple features, absolute values are used.

Closing

A dilation followed by an erosion. A morphological operator useful to close holes and boundaries.

C-mount

A threaded means of mounting a lens to a camera.

Coaxial Cable

A particular type of cable capable of passing a wide range of frequencies with very low signal loss. Such a cable in its simplest form, consists of a hollow metallic shield with a single wire accurately placed along the center of the shield and isolated from the shield.

Coaxial Illumination

Front lighting with the illumination path running along the imaging optical axis and usually introduced with a 45 degree angle beam splitter.

Coherent Fiber Optics

A bundle of optical fibers with the input and output spatial x-y relationship maintained, resulting in near spatially correct image transmission.

Collimate

To produce light with parallel rays.

Collimated Lighting

Radiation from a given point with every light ray considered parallel. In actuality, even light from a very distant point source (ie a star) diverges somewhat. Note that all collimators have some aberrations.

Color

A visual object attribute which may be described by a "coordinate system" such as hue, saturation and intensity (HSI), CIE or LAB. Wavelengths in the visible part of the electromagnetic spectrum to which retinal rods respond.

Color Burst

That portion of the composite color signal, comprising a few cycles of a sine wave of chrominance subcarrier frequency, which is used to establish a reference for demodulating the chrominance signal. Normally approximately 9 cycles of 3.579545 MHz.

Color calibration

The process of ensuring accurate reproduction of color for images. Full color calibration is usually a two-step process: calibrating your input device, such as a scanner or camera; and calibrating your output device, such as a printer or monitor. By calibrating input and output devices correctly, color is accurately captured by your scanner/camera and is reproduced faithfully on your monitor or printer as well.

Color Encoder

A device which produces an NTSC color signal from separate R, G, and B video inputs.

Color Saturation

The degree to which a color is free of white light.

Color Space

A two or three dimensional space used to represent an absolute color coordinate. RGB, HSI, LAB and CIE are all representations of color spaces.

Color Sync Signal

A signal used to establish and to maintain the same color relationships that are transmitted.

Color Temperature

A colorimetric concept related to the apparent visual color of a source, but not its actual temperature.

Colorimetry

Techniques used to measure color of an object or region and to define the results in a comparison or coordinate system.

Composite Video

A television signal which is produced by combining both a video or picture signal with horizontal and vertical synch and blanking signals.

Condenser Lens

Used to collect and redirect light for the purpose of illumination. Often used to collect light from a small source and project even light onto an object.

Connectivity Analysis

An SRI routine used to determine which pixels are interconnected and part of the same object or region. The results are used for blob analysis.

Contrast

The difference of light intensity between two adjacent regions in the image of an object. Often expressed as the difference between the lightest and darkest portion of an image. Contrast between a flaw or feature and its background is the goal of illumination.

Contrast Enhancement

Stretching of the gray level values between dark and light portions of an image to improve both visibility and feature detection.

Convergence

The crossover of the three electron beams of a three-gun tri-color picture tube. This normally occurs at the plane of the aperture mask.

Convolution

Superimposing a m x n operator (usually a 3x3 or 5x5 mask) over an area of the image, multiplying the points together, summing the results to replace the original pixel with the new value. This operation is often performed on the entire image to enhance edges, features, remove noise and other filtering operations.

Correlation

A mathematical measure of the similarity between images or areas within an image. Pattern matching or correlation of an X by Y array size template to the same size image, produces a scaler number, the percentage of match. Typically, the template is walked through a larger array to find the highest match.

CPU

An acronym for Central Processing Unit. A VLSI chip such as 80486 or Pentium.

Cross section

A 3D profile of a slice of an object.

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Darkfield Illumination

Lighting of objects, surfaces or particles at very shallow or low angles, so that light does not directly enter the optics. Objects are bright with a dark background. This grazing illumination causes specular reflections from abrupt surface irregularities.

Data Reduction

The process of lowering the data content of an pixel or image such as thresholding or run length encoding.

dB

Basically, a measure of the power ratio of two signals. In system use, a measure of the voltage ratio of two signals, provided they are measured across a common impedance.

Decision Tree

A structural classification technique based on relationships of feature measurements. Useful for differentiating a number of objects.

Dedicated System

Refers to a system which is configured for a specific application. Able to function when plugged in with no further development. Also called turnkey.

Depth of field

The range of an imaging system in which objects are in focus (the amount of focal tolerance in the object plane (frontal conjugate)).

Depth of focus

The amount of focal tolerance in the focal plane (rear conjugate).

Depth Perception (3D)

Measurement of the third dimension of an object or scene.

Dichroic Filter

A filter used to transmit light based on its wavelength, rather than on its plane of vibration. Transmits one color, while reflecting a second when illuminated with white light. Often used in heads-up displays.

Diffraction Pattern Sampling

Inspection by comparing portions of the interference pattern formed on a screen or special sensor from light waves diffracted by object edges.

Diffuse Reflection

Light which bounces off an object surface in many different directions. Light radiated from a matte surface is highly diffused.

Diffused lighting

Scattered soft lighting from a wide variety of angles used to eliminate shadows and specular glints from profiled, highly reflective surfaces.

Digital Camera

The newest generation of video cameras transform visual information into pixels, then translate each pixel's level of light into a number in the camera.

Digital Image

A video image converted into pixels. The numeric value of each pixel's value can be stored in a computer memory for subsequent processing and analysis.

Digital Signal Processor (DSP)

A VLSI chip designed for ultra high speed arithmetic processing. Often imbedded in a vision engine. TI's TMS320C40 is the industry standard.

Digital to analog converter

A VLSI circuit used to convert digital computer processed images to analog for display on a monitor. DAC is the acronym.

Digitization

Sampling and conversion of an incoming video or other analog signal into a digital value for subsequent storage and processing.

Dilation

A morphological operation which moves a probe or structuring element of a particular shape over the image, pixel by pixel. When an object boundary is contacted by the probe, a pixel is preserved in the output image. The effect is to "grow" the objects.

Dispersion

Separation of a beam of light into its wavelength components, each of which travel at slightly different speeds. Also called chromatic dispersion.

Distribution Amplifier

A device that provides several isolated outputs from one looping or bridging input, and has a sufficiently high input impedance and input-to-output isolation to prevent loading of the input source.

Dpi

Stands for dots per inch, the measure of resolution. The greater the dpi number, the higher the resolution.

Dust

An environmental contaminant consisting of airborne particles to be dealt with in machine vision. Never use factory air to keep optical surfaces clean, since oil will deposit.

Dynamic Range

The measure of the range light sensitivity a sensor is able to reproduce, from the darkest to the brightest portion of a scene. Usually expressed in decibels.

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Edge

A change in pixel values exceeding some threshold amount. Edges represent borders between regions on an object or in a scene.

Edge Detection

The ability to determine the true edge of an object.

Edge Operator

Templates for finding edges in images.

Electrical Noise

Interference from various electrical devices which is present in the air as electromagnetic radiation or rides on the power lines and can introduce error into low voltage computations such as A/D conversion.

Electro

The total range of wavelengths, extending from the longest (audio) to the shortest (gamma rays) which can be physically generated. This entire spectrum is potentially useful for imaging, well beyond just the visible spectrum.

Encoder (Shaft or position)

Provides rotation information for control of image acquisition, especially for moving web processes. Outputs either pulses for counting or BCD parallel with absolute position information.

Endoscope

A medical instrument used to view inside the human body. It may use borescope optics or coherent fibers to relay the image to the eye or camera. Illumination is provided by a non-coherent bundle of optical fibers.

Erosion

The converse of the morphology dilation operator. A morphological operation which moves a probe or structuring element of a particular shape over the image, pixel by pixel. When the probe fits inside an object boundary, a pixel is preserved in the output image. The effect is to "shrink or erode" objects as they appear in the output image. Any shape smaller than the probe (ie noise) disappears.

Exposure

The amount of light in an image. The exposure of an image can be changed by increasing or reducing available light.

Extension Tube

A cylindrical threaded tube used to change the magnification, effective focal length and field of view of a lens when inserted between the lens and imaging sensor.

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F number or f stop

The ratio of the focal length to the lens aperture. The smaller the f -number, the larger the lens diameter and brighter the image and narrower the depth-of-field

Fast Fourier Transform

Produces a new image which represents the frequency domain content of the spatial or time domain image information. Data is represented as a series of sinusoidal waves.

Feature Extraction

Determining image features by applying feature detectors to distinguish or segment them from the background.

Feature Vectors

A set of features of an object (such as area, number of holes, etc) that can be used for its identification or inspection.

Features

Simple image data attributes such as pixel amplitudes, edge point locations and textural descriptors, center of mass, number of holes in an object with distinctive characteristics defined by boundaries or regions.

Fiber Optics

Light source or optical image delivery via a long, flexible fiber(s) of transparent material, usually bundled together. Light is transmitted via internal reflection inside each fiber. Coherent fiber optics are spatially organized so images can be relayed.

Fiberscope

An optical instrument similar to a borescope, but uses a flexible, coherent fiber or bundle (usually silicon), an objective lens and an eyepiece or camera.

Fiducial

A line, mark or shape used as a standard of reference for measurement or location.

Field

One of the two parts of a television frame in an interlaced scanning system. The odd plus the even field comprise one video frame. A field is scanned every 1/60th of a second.

Field of view

The 2D area which can be seen through the optical imaging system. (FOV)

File format

The way a graphic file is saved. Several file formats are available for use, and each one has its own advantages and disadvantages. The most popular file formats include JPEG, GIF, BMP, TIFF, PICT, EPS, and PCX. TIFF is the most widely used file format.

Filter

A device or process that selectively transmits frequencies. In optics, the material either reflects or absorbs certain wavelengths of light, while passing others.

Filtering

The use of an optical filter for picture or color enhancement in front of the camera lens or light source. Also analog or digital image processing (IP) operations to enhance or modify an image. May be linear & non linear.

Filters

Tools that allow you to apply or create special effects to your images. Filters in your software include Blur/Blur More, Sharpen/Sharpen More, Emboss, and Edge Enhancement.

Firmware

Software hard coded in non volitle memory (ROM), usually to increase speed.

Fixture

A device to hold and locate a workpiece during processing or inspection operations.

Fluorescence

The emission of light or other electromagnetic radiation at longer wavelengths by matter as a result of absorption of a shorter wavelength. The emission lasts only as long as the stimulating irradiation is present.

Focal Length

The distance from a lens' principal point to the corresponding focal point on the object.

Focal Plane

Usually found at the image sensor, it is a plane perpendicular to the lens axis at the point of focus .

Focus

The point at which rays of light converge for any given point on the object in the image. Also called the focal point.

Focus Following

A ranging and tracking technique that uses image processing to measure object range based on best focus.

Footlambert (FL)

A unit of luminance equal to 1/candela per square foot or to the uniform luminance at a perfectly diffusing surface emitting or reflecting light at the rate of one lumen per square foot. A lumen per square foot is a unit of incident light and a footlambert is a unit of emitted or reflected light. For a perfectly reflecting and perfectly diffusing surface, the number of lumens per square foot is equal to the number of footlamberts.

Fourier Domain Inspection

Evaluation of the fourier transform (frequency information) of a 2D spatial image for features of interest.

Frame

The total area scanned in an image sensor while the video signal is not blanked. In interlaced scanning, two fields comprise one frame. Frame rate is typically 30 Hz.

Frame Buffer

Image memory in a frame grabber.

Frame Grabber

A device that interfaces with a video camera and, on command, samples the video, converts the video image into digital values and stores that array of numbers in the computer's memory.

Frame Transfer

A CCD imager where an entire matrix of pixels is read into storage before being output from the camera. Differs from Interline Transfer where lines of pixels are output

Front End System

The object, illumination, optics and imager blocks of a vision system. Includes all components useful to acquire a good image for subsequent processing.

Front Lighting

The use of illumination on the camera side of an object so that surface features can be observed.

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Gaging

In machine vision, non contact dimensional examination of an object.

Gamma (,)

The numeric value for the degree of contrast in a television picture. The exponent in the power law relating output to input signal magnitude. Non linear camera tube. Or simply, the contrast affecting the mid level grays or midtones of an image. Adjusting the gamma of an image allows you to change brightness values of the middle range of gray tones without dramatically altering the shadows and highlights.

Glints

Shiny, specular reflections from smooth objects or surfaces.

Global Method

An image processing operation uniformly applied to the whole image.

Gradient

The rate of change of pixel intensity (first derivative).

Gradient Space

A matrix containing values for the rate of change of pixel values or gray level intensity of the image.

Gradient Vector

The orientation and magnitude of the rate of change in intensity at a point or pixel location in the image.

Grating

An optical element with an even arrangement of rods or stripes with spaces between them for light to pass. Its ability to separate wavelengths is expressed in line pairs per millimeter, for example. A moire grating of parallel dark and light stripes is an example. Also used for structured light projection.

Gray level

A quantized measurement of image irradiance (brightness), or other pixel property typically in the range between pure white and black.

Grayscale Image

An image consisting of an array of pixels which can have more than two values. Typically, up to 256 levels (8 bits) are used for each pixel.

GUI

An acronym for Graphical User Interface. Pronounced "gooie." A Windows based user interface screen or series of screens allowing the user to point-and-click to select icons rather than typing commands.

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Halftone

A type of single bit image composed of a pattern of black dots that fool the eye into seeing shades of gray. Examples of halftone images are the pictures you see in a newspaper. These images usually look very coarse.

Halogen lamp

An incandescent lamp with a gas similar to iodine inside which is constantly evaporated then redeposited on the filament.

Hardware

Electronic integrated circuits, boards and systems used by the system.

HDTV

High Definition TV proposed broadcast standard to double the current 525 lines per picture to 1,050 lines, and increasing the screen aspect ratio from 12:9 to 16:9. The typical TV of 336,00 pixels would increase to about 2 million.

Height/Range

Object profile is usually measured by changes in range or distances from the sensor. 3D techniques are usually used.

High Pass Filter

Passes detailed high frequency image information, while attenuating low frequency, slow changing data.

High Speed Imaging

Image capture near, at or above 1800 parts per minute.

Histogram

A graphical representation of the frequency of occurrence of each intensity or range of intensities (gray levels) of pixels in an image. The height represents the number of observations occurring in each interval. A histogram skewed heavily to the left indicates a dark image, while a histogram skewed to the right indicates a light image.

Histogram Analysis

Determination of the presence or absence of a feature or flaw based on the histogram values in a certain gray scale region.

Histogram Equalization

Modification of the histogram to evenly distribute a narrow range of image gray scale values across the entire available range.

Holography

Optically recording of the interference pattern from two coherent waves which forms a 3 dimensional record or hologram.

Hough Transform

A global parallel method for locating both curved and straight lines. All points on the curve map into a single location in the transform space.

HSI

An acronym for the Hue, Saturation and Intensity color representation. A mathematical conversion from RGB. Often used for machine vision analysis.

HSI Conversion

A mathematical conversion from the color RGB space to hue, saturation and intensity values.

Hue

One of the three properties of HSI color perception. A color attribute used to express the amount of red, green, blue or yellow a certain color possesses. White, gray and black do not exhibit any hue.

Hueckel Operator

An edge finding operator which fits an intensity surface to the neighborhood of each pixel and selects surface gradients above a specified threshold.

Hybrid Electro

Optic Sensor A silicon sensor fabricated in a configuration to match spatial information generated by the imaging system, such as a PSD (position sensitive detector), concentric rings, pie shapes and others.